1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method for manufacturing an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus having an electrophotographic photosensitive member.
2. Related Background Art
For electrophotographic photosensitive members, electrophotographic photosensitive members made by providing on a cylindrical support a photosensitive layer (organic photosensitive layer) using an organic material as a photoconductive material (charge generation material and charge transport material), so called organic electrophotographic photosensitive members have come into wide use because of their advantages of low costs, high productivity and the like. For organic electrophotographic photosensitive members, electrophotographic photosensitive members having a photosensitive layer made by stacking a charge generation layer containing a charge generation material such as a photoconductive dye or photoconductive pigment and a charge transport layer containing a charge transport material such as a photoconductive polymer or photoconductive low molecule compound, so called a multi-layer photosensitive layer, are mainstream because of their advantages of high sensitivity, high durability and the like.
For electrophotographic photosensitive members, cylindrical electrophotographic photosensitive members made by providing a photosensitive layer on a cylindrical support are generally used.
Since electric external forces and/or mechanical external forces from charging (primary charging), exposure (image exposure), development by a toner, transfer onto a transfer material such as paper, and cleaning of a transfer residual toner are applied directly to the peripheral surface (surface) of the electrophotographic photosensitive member, the electrophotographic photosensitive member is required to have durability to these external forces. Specifically, the electrophotographic photosensitive member is required to have durability to occurrence of scars and wear resulting from the external forces, i.e. scratch resistance and wear resistance.
For the technique for improving the scratch resistance and wear resistance of the peripheral surface of the organic electrophotographic photosensitive member, for example, an electrophotographic photosensitive member in which a cured layer using a curable resin as a binding resin is used as a surface layer (a layer located at the outermost surface of the electrophotographic photosensitive member, in other words, a layer at a greatest distance from the support) is disclosed in Japanese Patent Application Laid-Open No H02-127652.
An electrophotographic photosensitive member in which a cured charge transport layer formed by curing polymerization of a monomer having a carbon-carbon double bond and a charge transporting monomer having a carbon-carbon double bond by heat or light energy is used as a surface layer is disclosed in Japanese Patent Application Laid-Open No. H05-216249 and Japanese Patent Application Laid-Open No. H07-072640.
An electrophotographic photosensitive member in which a cured charge transport layer formed by curing polymerization of positive hole transporting compound having a chain polymerizable functional group in its molecule by electron beam energy is used as a surface layer is disclosed Japanese Patent Application Laid-Open No. 2000-066424 and Japanese Patent Application Laid-Open No. 2000-066425.
In this way, as a technique for improving the scratch resistance and wear resistance of the peripheral surface of the organic electrophotographic photosensitive member, a technique in which a cured layer is used as a surface layer of the electrophotographic photosensitive member, whereby the mechanical strength of the surface layer is enhanced has been established in recent years.
The electrophotographic photosensitive member is used in an electrophotographic image formation process consisting of a charging step, an exposure step, a development step, a transfer step and a cleaning step as described above.
In the electrophotographic image formation process, the cleaning step of cleaning the peripheral surface of the electrophotographic photosensitive member by removing a toner remaining on the electrophotographic photosensitive member after the transfer step, so called a transfer residual toner is a step important for obtaining a clear image.
For the cleaning method, a method in which a cleaning blade is abutted against the electrophotographic photosensitive member to eliminate a gap between the cleaning blade and the electrophotographic photosensitive member, and leakage or slipping-through of the toner is thus prevented, whereby the transfer residual toner is scraped off is mainstream because of advantages of costs and ease of design.
Particularly, if a full color image is formed, the amount of toner used is much larger than the amount of toner used when a monochrome image is formed because toners of multiple colors such as magenta, cyan, yellow and black are superimposed on one after another to reproduce a desired color, and therefore a cleaning method using a cleaning blade is most suitable.
However, the cleaning method using a cleaning blade has a disadvantage that the cleaning blade tends to chatter and wear out because of strong friction between the cleaning blade and the electrophotographic photosensitive member. The chatter of the cleaning blade is a phenomenon in which the cleaning blade vibrates due to an increase in friction resistance between the cleaning blade and the peripheral surface of the electrophotographic photosensitive member, and the wear-out of the cleaning blade is a phenomenon in which the cleaning blade is inverted in a direction along which the electrophotographic photosensitive member travels.
These problems of the cleaning blade become more significant as the mechanical strength of the surface layer of the electrophotographic photosensitive member increases, i.e. the peripheral surface of the electrophotographic photosensitive member becomes hard to be worn.
The surface layer of the organic electrophotographic photosensitive member is often formed by a dip coating method in general, but the surface of the surface layer, i.e. the peripheral surface of the electrophotographic photosensitive member formed by the dip coating method is very flat, an area of contact between the cleaning blade and the peripheral surface of the electrophotographic photosensitive member therefore increases, and friction resistance between the cleaning blade and the peripheral surface of the electrophotographic photosensitive member increases, thus making the above problems more significant.
As one method for overcoming the chatter and wear-out of the cleaning blade, a method in which the peripheral surface of the electrophotographic photosensitive member is appropriately roughened is known.
For the technique for roughening the peripheral surface of the electrophotographic photosensitive member, for example, a technique in which the surface roughness (roughness of peripheral surface) of the electrophotographic photosensitive member is limited within a specified range for facilitating separation of a transfer material from the peripheral surface of the electrophotographic photosensitive member is disclosed in Japanese Patent Application Laid-Open No. S53-092133. A method in which the peripheral surface of the electrophotographic photosensitive member is roughened into an orange peel surface by controlling drying conditions in formation of the surface layer is disclosed in Japanese Patent Application Laid-Open No. S53-092133.
A technique in which particles are incorporated in the surface layer to roughen the peripheral surface of the electrophotographic photosensitive member is disclosed in Japanese Patent Application Laid-Open No. S52-026226.
A technique in which the peripheral surface of the electrophotographic photosensitive member is roughened by polishing the surface of the surface layer using a metal wire blush is disclosed in Japanese Patent Application Laid-Open No. S57-094772.
A technique in which the peripheral surface of the organic electrophotographic photosensitive member is roughened for solving the invert (wear-out) of the cleaning blade and chipping of an edge portion which raise a problem when the electrophotographic photosensitive member is used with an electrophotographic apparatus of specific process speed or greater, by using specific cleaning means and toners is disclosed in Japanese Patent Application Laid-Open No. H01-099060.
A technique in which the peripheral surface of the electrophotographic photosensitive member is roughened by polishing the surface of the surface layer using a film-shaped polishing material is disclosed in Japanese Patent Application Laid-Open No. H02-139566.
A technique in which the peripheral surface of the electrophotographic photosensitive member is roughened by a blast process is disclosed in Japanese Patent Application Laid-Open No. H02-150850. However, the shape of the peripheral surface of the electrophotographic photosensitive member roughened in this way is unknown.
However, the above prior art techniques could not sufficiently solve the problems of chatter and wear-out of the cleaning blade described above.
If friction of the peripheral surface of the electrophotographic photosensitive member is strong, a problem of a rubbing memory tends to occur when pre-rotation is performed without charging and exposure, but the above prior art techniques could not sufficiently solve the problem.